1. Field of Use
The present invention is related to a device and method for improvement of sleep testing and sleep therapy using acoustic diagnostic methods to examine various aspects of a subject's sleep quality. More particularly, the method and device of the present invention includes the use of an acoustic actuator and an acoustic sensor to acoustically monitor the state of a subject's airway during sleep in order to determine airway obstructions and their locations as they relate to a subject's sleep stage, body position and sleep quality.
2. Technology Review
Nearly one in seven people in the United States suffer from some type of chronic sleep disorder, and only 50% of people are estimated to get the recommended seven to eight hours of sleep each night. It is further estimated that sleep deprivation and its associated medical and social costs (loss of productivity, industrial accidents, etc.) exceed $150 billion per year. Excessive sleepiness can deteriorate quality of life and is a major cause of morbidity and mortality due to its role in industrial and transportation accidents. Sleepiness further has undesirable effects on motor vehicle operation, employment, higher earning and job promotion opportunities, education, recreation, and personal life.
Primary sleep disorders affect approximately 50 million Americans of all ages and include narcolepsy, restless legs/periodic leg movement, insomnia, and, most commonly, obstructive sleep apnea (OSA). OSA's prevalence in society is comparable to that of diabetes, asthma, and the lifetime risk of colon cancer. OSA is grossly under diagnosed with an estimated 80-90% of persons afflicted having not received a clinical diagnosis.
Although various methods exist to diagnose sleep disorders, the most common method of diagnosis of primary sleep disorders is the use of sleep testing. Sleep testing, or conducting a sleep study, involves the use of a combination of sensors and various physiological measurements to examine a subject's sleep health. In its simplest form, sleep testing can consist of the use of a single sensor to monitor a subject's sleep quality. More commonly, sleep testing is conducted using at least three sensors for measuring respiratory effort, heart rate, and blood oxygen saturation. In more complex forms, sleep testing can include the addition of sensors for measuring brain activity, airflow and muscle activity. One example of this is all-night polysomnography (PSG) which includes the use of brain and muscle activity measurements to perform sleep staging during a sleep study.
Notwithstanding the many types of sensors commonly used to monitor physical and physiological variables during a sleep study, currently, no viable methods exist to accurately and conveniently localize the location of airway obstructions while a subject sleeps during a sleep test or sleep therapy procedure. Although a number of airway imaging modalities exist, including cephalometry, computed tomography and pharyngometry, these cannot practically be used while a subject sleeps because of the nature of the equipment required to perform these procedures. Other imaging methods, such as sleep endoscopy and esophageal manometry, may be used while a subject sleeps, but are costly, ineffective and invasive, as they require placement of nasal catheters or endoscopes into the pharynx of a subject under local anesthetic for prolonged periods of time, and positioning of the patient. These procedures are thus used on a limited basis and are not in practice correlated with other parameters related to sleep quality.
To address these shortcomings, it is therefore an object of the present invention to provide a device and method for convenient, non-invasive monitoring of airway state while a subject sleeps during sleep testing and sleep therapy procedures. It is another object of the present invention to provide a method and device wherein an acoustic generator and acoustic sensor placed near the mouth of a subject collect information on the nature and location of obstructive tissue within a subject's airway. It is another object of the present invention to provide a method and device by which information pertaining to the nature and location of obstructive tissue within a subject's airway is used in surgical planning to determine the tissue to be removed or extracted during surgery. It is still another object of the present invention to provide a method and device wherein information pertaining to the nature and location of obstructive tissue within a subject's airway is used to modulate a positive airway pressure device during positive airway pressure therapeutic and diagnostic procedures. It is still another object of the present invention to correlate obstruction location with other sensors used to determine sleep quality to better understand the basis for the obstruction. It is still another object of the present invention to use location or size of obstruction information to titrate treatment of the subject.